Jouni Tuominen

Manuscripts are a crucial form of evidence for research into all aspects of premodern European history and culture, and there are numerous databases devoted to describing them in detail. This descriptive information, however, is typically available only in separate data silos based on incompatible data models and user interfaces. As a result, it has been difficult to study manuscripts comprehensively across these various platforms. To address this challenge, a team of manuscript scholars and computer scientists worked to create “Mapping Manuscript Migrations” (MMM), a semantic portal, and a Linked Open Data service. MMM stands as a successful proof of concept for integrating distinct manuscript datasets into a shared platform for research and discovery with the potential for future expansion. This paper will discuss the major products of the MMM project: a unified data model, a repeatable data transformation pipeline, a Linked Open Data knowledge graph, and a Semantic Web portal. It will also examine the crucial importance of an iterative process of multidisciplinary collaboration embedded throughout the project, enabling humanities researchers to shape the development of a digital platform and tools, while also enabling the same researchers to ask more sophisticated and comprehensive research questions of the aggregated data.

The Second World War (WW2) is arguably the most devastating catastrophe of human history, a topic of great interest to not only researchers but the general public. However, data about the Second World War is heterogeneous and distributed in various organizations and countries making it hard to utilize. In order to create aggregated global views of the war, a shared ontology and data infrastructure is needed to harmonize information in various data silos. This makes it possible to share data between publishers and application developers, to support data analysis in Digital Humanities research, and to develop data-driven intelligent applications. As a first step towards these goals, this article presents the WarSampo knowledge graph (KG), a shared semantic infrastructure, and a Linked Open Data (LOD) service for publishing data about WW2, with a focus on Finnish military history. The shared semantic infrastructure is based on the idea of representing war as a spatio-temporal sequence of events that soldiers, military units, and other actors participate in. The used metadata schema is an extension of CIDOC CRM, supplemented by various military historical domain ontologies. With an infrastructure containing shared ontologies, maintaining the interlinked data brings upon new challenges, as one change in an ontology can propagate across several datasets that use it. To support sustainability, a repeatable automatic data transformation and linking pipeline has been created for rebuilding the whole WarSampo KG from the individual source datasets. The WarSampo KG is hosted on a data service based on W3C Semantic Web standards and best practices, including content negotiation, SPARQL API, download, automatic documentation, and other services supporting the reuse of the data. The WarSampo KG, a part of the international LOD Cloud and totalling ca. 14 million triples, is in use in nine end-user application views of the WarSampo portal, which has had over 400 000 end users since its opening in 2015.

Governments publish legislation and case law widely in print and on the Web. Such legal information is provided for human consumption, but the information is usually not available as data for algorithmic analysis and applications to use. However, this would be beneficial in many use cases, such as building more intelligent juridical online services and conducting research into legislation and legal practice. To address these needs, this Chapter presents Semantic Finlex, a national in-use data resource and service for publishing Finnish legislation and related case law as Linked Open Data for legal applications to use. The system transforms and interlinks on a regular basis data from the legacy legal database Finlex of the Ministry of Justice into Linked Open Data, based on the European standards ECLI and ELI. The published data is hosted on the 7-star Linked Data Finland service and SPARQL endpoint with a variety of related services available that ease data re-use. Rich Internet Applications using SPARQL for data access are presented as application demonstrators of the data service. In addition, this Chapter presents methods and tools under development to automatically annotate legal texts and to anonymize case law documents prior to their publication on the Web. Anonymization is necessary due to issues of data protection and privacy, and annotation is needed for semantic search and interlinking the documents. The automated approaches could significantly speed up the process and minimize costs of publishing legal documents as Linked Open Data.

WarSampo Knowledge Graph includes harmonized data of different kinds concerning the Second World War in Finland, separated in different subgraphs representing events, actors, places, photographs, and other aspects and documentation of the war. The data covers the Winter War 1939-1940 against the Soviet attack, the Continuation War 1941-1944 where the occupied areas of the Winter War were temporarily regained, and the Lapland War 1944-1945, where the Finns pushed the German troops away from Lapland.

This paper introduces AMMO Ontology of Finnish Historical Occupations. AMMO is based on thousands of occupation labels extracted from three Finnish military historical datasets of the early 20th century: the first consists of the ca. 40 000 war-related death records around the time of the Finnish Civil War (1914–1922); the second consists of the ca. 95 000 death records of Finnish soldiers in the Winter War and Continuation War (1939–1944); the third contains the ca. 4500 records of Finnish prisoners of war in the Soviet Union during the WW2. Our goal from a Digital Humanities perspective is to use AMMO to study military history and these datasets based on the occupation and social status of the soldiers. AMMO will also be used as a component for faceted search and semantic recommendation in two semantic portals for Finnish military history. AMMO is aligned with the international historical occupation classification HISCO and with a modern Finnish occupational classification for international and national interoperability. The ontology is published as Linked Open Data in an ontology service.

Biographies make a promising application case of Linked Data: they can be used, e.g., as a basis for Digital Humanities research in prosopography and as a key data and linking resource in semantic Cultural Heritage (CH) portals. In both use cases, a semantic data model for harmonizing and interlinking heterogeneous data from different sources is needed. This paper presents such a data model, Bio CRM, with the following key ideas: 1) The model is a domain specific extension of CIDOC CRM, making it applicable to not only biographical data but to other CH data, too. 2) The model makes a distinction between enduring unary roles of actors, their enduring binary relationships, and perduing events, where the participants can take different roles modeled as a role concept hierarchy. 3) The model can be used as a basis for semantic data validation and enrichment by reasoning. 4) The enriched data conforming to Bio CRM is targeted to be used by SPARQL queries in a flexible ways using a hierarchy of roles in which participants can be involved in events.

This paper shows how faceted search on biographical data can be utilized as a flexible basis for filtering target groups of people and, in particular, how generic data analysis and visualization tools can then be applied for solving prosopographical research questions based on the filtered data. This idea is demonstrated and evaluated in practice by presenting two application case studies: 1) linked data extracted from a printed registry of over 10 000 alumni (1867–1992) of the prominent Finnish high school Norssi, and 2) a knowledge graph extracted from 13 000 short biographies of significant Finnish people (from 3rd century to present times) in the National Biography of Finland. In both cases, the data is enriched by linking their entities with several other external datasets.

This paper presents a series of projects where one of the main sources for toponomastic research in Finland, the corpora of place names in the Names Archive database of the Institute for the Languages of Finland, was digitized and how the resulting database was converted, enriched and published as Linked Open Data using a data processing pipeline. Utilizing the Linked Data infrastructure and various external data sources, a modern full-stack web application, NameSampo, was created in collaboration between toponomastic researchers and computer scientists for searching, analyzing, and visualizing digital toponomastic data sources.

Biografiasampo-järjestelmä käynnistää uuden aikakauden elämäkertakokoelmien julkaisemisessa ja käyttämisessä verkossa. Järjestelmän ydinaineistona on Kansallisbiografia ja muut Suomalaisen Kirjallisuuden Seuran (SKS) ja tieteellisten seurojen toimittamat pienoiselämäkerrat, yhteensä 13 100 elämäntarinaa, joita on kirjoittanut 900 suomalaista tutkijaa. Biografiasammon innovaationa on luoda kieliteknologian, tekoälyn ja semanttisen webin teknologioiden avulla elämäkertojen teksteistä ja niihin eri lähteissä liittyvistä tiedoista tietämysverkko (knowledge graph) ja kansallinen tietoinfrastruktuuri, joka koostuu miljoonista tietojen välisistä yhteyksistä. Tietämysverkko on julkaistu linkitetyn datan palvelussa, jonka varaan on toteutettu seitsemästä sovellusnäkymästä koostuva älykäs, kaikille avoin ja maksuton verkkopalvelu biografiasampo.fi kansalaisten ja digitaalisten ihmistieteiden tutkijoiden käytettäväksi.

This paper presents the vision of publishing and utilizing textual biographies as Linked (Open) Data on the Semantic Web. As a case study, we publish the live stories of the National Biography of Finland, created by the Finnish Literature Society, as semantic, i.e., machine “understandable” metadata in a SPARQL endpoint using the Linked Data Finland (LDF.fi) service. On top of the data service various Digital Humanities applications are built. The applications include searching and studying individual personal histories as well as historical research of groups of persons using methods of prosopography. The biographical data is enriched by extracting events from unstructured and semi-structured texts, and by linking entities internally and to external data sources. A faceted semantic search engine is provided for filtering groups of people from the data for prosopographical research. An extension of the event-based CIDOC CRM ontology is used as the underlying data model, where lives are seen as chains of interlinked events populated from the data of the biographies and additional data sources, such as museum collections, library databases, and archives.

Between 1500 and 1800, a revolution in postal communication allowed ordinary men and women to scatter letters across and beyond Europe. This exchange helped knit together what contemporaries called the respublica litteraria, Republic of Letters, a knowledge-based civil society, crucial to that era’s intellectual breakthroughs, and formative of many modern European values and institutions. To enable effective Digital Humanities research on the epistolary data distributed in different countries and collections, metadata about the letters have been aggregated, harmonised, and provided for the research community through the Early Modern Letters Online (EMLO) service. This paper discusses the idea and benefits of using Linked Data as a basis for the next digital framework of EMLO, and presents experiences of a first demonstrational implementation of such a system.

War history of the Second World War (WW2), humankind’s largest disaster, is of great interest to both laymen and researchers. Most of us have ancestors and relatives who participated in the war, and in the worst case got killed. Researchers are eager to find out what actually happened then, and even more importantly why, so that future wars could perhaps be prevented. The darkest data of war history are casualty records—from such data we could perhaps learn most about the war. This paper presents a model and system for representing death records as linked data, so that 1) citizens could find out more easily what happened to their relatives during WW2 and 2) digital humanities (DH) researchers could (re)use the data easily for research.

This paper describes the ontology model and published datasets of a digitized biographical person register. The applied ontology model is designed to represent people via their enduring roles and perduring lifetime events. The model is designed to support 1) prosopographical Digital Humanities research, 2) linking to resources in semantic Cultural Heritage portals, and 3) semantic data validation and enrichment by using SPARQL queries. The linked data approach enables to enrich a person s biography by interlinking it with space and time related biographical events, persons relating by social contacts or family relations, historical events, and personal achievements.

This paper presents a model for representing historical military personnel and army units, based on large datasets about World War II in Finland. The model is in use in WarSampo data service and semantic portal, which has had tens of thousands of distinct visitors. A key challenge is how to represent ontological changes, since the ranks and units of military personnel, as well as the names and structures of army units change rapidly in wars. This leads to serious problems in both search as well as data linking due to ambiguity and homonymy of names. In our solution, actors are represented in terms of the events they participated in, which facilitates disambiguation of personnel and units in different spatio-temporal contexts. The linked data in the WarSampo Linked Open Data cloud and service has ca. 9 million triples, including actor datasets of ca. 100 000 soldiers and ca. 16 100 army units. To test the model in practice, an application for semantic search and recommending based on data linking was created, where the spatio-temporal life stories of individual soldiers can be reassembled dynamically by linking data from different datasets. An evaluation is presented showing promising results in terms of linking precision.

The article overviews the system WarSampo – Finnish World War 2 on the Semantic Web, the winner of the LODLAM Challenge 2017 Open Data Prize on June 29 in Venice, Italy.

This paper presents an automatic annotation tool AATOS for providing documents with semantic annotations. The tool links entities found from the texts to ontologies defined by the user. The application is highly configurable and can be used with different natural language Finnish texts. The application was developed as a part of WarSampo and Semantic Finlex projects and tested using Kansa Taisteli magazine articles and consolidated Finnish legislation of Semantic Finlex. The quality of the automatic annotation was evaluated by measuring precision and recall against existing manual annotations. The results showed that the quality of the input text, as well as the selection and configuration of the ontologies impacted the results.

This paper presents the idea to enrich printed biographical person registers with linked data related to events that took place after the register was published. By transforming printed historical documents into structured data, semantic search to written texts can be provided for the reader. Even more importantly, life stories of historical persons can be extended based on data linking by extracting semantic structures from printed texts, and by combining this data with external datasets and data services. Such linking provides an enriched context for prosopographical research on people in the register, as well as an enhanced reading experience for anyone interested in reading the biographies. As a concrete case study, a register 1867–1992 of over 10 000 alumni of the prominent Finnish high school “Norssi” was transformed into RDF, was enriched by data linking, was published as a linked data service, and is provided to end users via a faceted search engine and browser for studying lives of historical persons and for prosopographical research.

This paper discusses the challenges of applying named entity linking in a rich, complex domain – specifically, the linking of 1) military units, 2) places and 3) people in the context of rich Second World War data. Multiple sub-scenarios are discussed in detail through concrete evaluations, analyzing the problems faced, and the solutions developed. A key contribution of this work is to highlight the heterogeneity of problems and approaches needed even inside a single domain, depending on both the source data as well as the target authority.

Data about wars is typically heterogeneous, distributed in the data silos of the fighting parties, multilingual, and often controversial depending on the political point of view. It is therefore hard for the historians to get a global picture of what has actually happened, to whom, where, when, and how. We argue that Semantic Web and Linked Data technologies are a very promising approach for modeling, harmonizing, and aggregating data about war history. Our goal is to make it possible, for both historians and laymen, to study history in a contextualized way where linked datasets enrich each other. The paper presents the in-use WarSampo 1 system, where massive collections of heterogeneous data about the (Finnish) history of the Second World War are harmonized using an event-based approach, and provided as a Linked Open Data service for applications to use. As a use case, a semantic portal WarSampo providing six different perspectives to the war based on events is presented.

This paper presents the WarSampo system for publishing collections of heterogeneous, distributed data about the Second World War on the Semantic Web. WarSampo is based on harmonizing massive datasets using event-based modeling, which makes it possible to enrich datasets semantically with each others’ contents. WarSampo has two components: First, a Linked Open Data (LOD) service WarSampo Data for Digital Humanities (DH) research and for creating applications related to war history. Second, a semanticWarSampo Portal has been created to test and demonstrate the usability of the data service. The WarSampo Portal allows both historians and laymen to study war history and destinies of their family members in the war from different interlinked perspectives. Published in November 2015, theWarSampo Portal had some 20,000 distinct visitors during the first three days, showing that the public has a great interest in this kind of applications.

War history of the Second World War (WW2), humankind s largest disaster, is of great interest to both laymen and researchers. Most of us have ancestors and relatives who participated in the war, and in the worst case got killed. Researchers are eager to find out what actually happened then, and even more importantly why, so that future wars could perhaps be prevented. The darkest data of war history are casualty records---from such data we could perhaps learn most about the war. This paper presents a model and system for representing death records as linked data, so that 1) citizens could find out more easily what happened to their relatives during WW2 and 2) digital humanities (DH) researchers could (re)use the data easily for research.

This paper presents a new Linked Open Data brokering service model HIPLA for using and maintaining historical place gazetteers and maps based on distributed SPARQL endpoints. The model introduces several novelties: First, the service facilitates collaborative maintenance of geo-ontologies and maps in real time as a side effect of annotating contents in legacy cataloging systems. The idea is to support a collaborative ecosystem of curators that creates and maintains data about historical places and maps in a sustainable way. Second, in order to foster understanding of historical places, the places can be provided on both modern and historical maps, and with additional contextual Linked Data attached. Third, since data about historical places is typically maintained by different authorities and in different countries, the service can be used and extended in a federated fashion, by including new distributed SPARQL endpoints (or other web services with a suitable API) into the system. To test and demonstrate the model, we created the first prototype implementation Hipla.fi of the HIPLA model. Hipla.fi is based on four Finnish datasets in SPARQL endpoints totaling some 840,000 geocoded places on 450 historical maps from two atlas series aligned on modern maps, and on the Getty Thesaurus of Geographic Names (TGN) SPARQL endpoint in the US. As a first application, a part of the Hipla.fi data service has been applied in creating a 5 million triple semantic portal of historical Second World War data with tens of thousands of end users.

This paper initiates and fosters work on publishing Linked Open Data about the Second World War. It is argued that the heterogeneous, distributed data about the international world war history makes a promising use case for semantic technologies. We hope that by making war data openly available we can learn from the past and promote peace.

This paper introduces the idea of applying crowdsourcing to evolving ontology services; the goal is to facilitate collaborative maintenance of ontologies in real time as a side effect of annotating contents in legacy cataloging systems. The idea is being implemented in the use case of creating and managing a national level gazetteer of historical places in Finland.

The Finnish Ontology Library Service ONKI was published as a living laboratory prototype for public use in 2008. Its idea is to support content indexers and ontology developers via a browser interface and machine APIs. ONKI has been well-accepted, but being a prototype maintained by the ending research project FinnONTO (2003–2012), a more sustainable service was needed, supported by permanent governmental funding. To achieve this, ONKI was deployed and is being further developed by the National Library of Finland into a new national vocabulary service Finto. We discuss challenges in the deployment of ONKI into Finto and lessons learned during the transition process.

The idea of Linked Data is to aggregate, harmonize, integrate, enrich, and publish data for re-use on the Web in a cost-efficient way using Semantic Web technologies. We concern two major hindrances for re-using Linked Data: It is often difficult for a re-user to 1) understand the characteristics of the dataset and 2) evaluate the quality the data for the intended purpose. This paper introduces the “Linked Data Finland” platform LDF.fi addressing these issues. We extend the famous 5-star model of Tim Berners-Lee, with the sixth star for providing the dataset with a schema that explains the dataset, and the seventh star for validating the data against the schema. LDF.fi also automates data publishing and provides data curation tools. The first prototype of the platform is available on the web as a service, hosting tens of datasets and supporting several applications.

The idea of opening data on the Web as Linked Data (LD) is widely adopted in areas such as public government, science, libraries, and cultural heritage. The key idea is to harmonize, integrate, enrich, and re-use existing data repositories in a cost-efficient way via standard APIs in novel applications. This paper concerns two major hindrances for re-using LD: It is often difficult for a re-user to understand the 1) characteristics of the dataset and 2) evaluate the quality of the data for her intended purpose. This paper introduces the “Linked Data Finland” publishing platform LDF.fi addressing these issues. In order to enhance and promote reusability, we propose extending the famous 5-star model of Tim Berners-Lee into a 7-star model: The sixth star requires that the dataset is defined and explained in terms of explicit schemas. Explicit schemas make it possible to explain the re-user the intended characteristics of the data by, e.g., documentation about the schemas, and how the schemas (vocabularies) are actually used in the given dataset. The seventh star is given, if the data has also been validated w.r.t. the schema specifications. The results of the validation may be a human readable document and/or a machine readable reprentation regarding the quality issues found in the data. This paper reports about work in progress, but the first prototype of the platform is already operational on the web as a service http://ldf.fi.

We present an ontology for managing the scientific and common names of birds. The ontology is based on the TaxMeOn meta-ontology model for biological names. The ontology is in use as an ontology service and it has been applied in a bird watching system.

Juridical information is important to organizations and individuals alike and is linked to from all walks of life. The Finnish government has published the Finlex Data Bank for searching and browsing legislation documents. However, the data there is not yet open, is based on a traditional XML schema, and does not conform to new semantic metadata standards. There are many difficulties in maintaining and using the site in, e.g., data harvesting, interoperability, querying, and linking that could be mitigated by the Semantic Web technologies. This paper presents an approach and a project—including first results—for publishing and using Finnish legislation as a 5-star Linked Open Data service.

Observational data about species of public interest, such as birds and butterflies, is often created and collected by volunteered citizen scientists, and used by professionals for managing biodiversity. The education and skills of the citizens participating in the work varies a lot, and the process of making observations is typically not systematic but rather ad hoc. As a result, the quality of the observational data in repositories, such as the Global Biodiversity Information Facility GBIF Data Portal, is often not good, hampering its utilization severely. This paper presents an approach for enhancing data quality in a citizen science setting, and presents a mobile tool BirdWatch for citizen observers, mitigating difficulties in producing high quality Linked Data for biodiversity management.

Animals and plants are referred to using scientific or common names depending on the expertise of an audience or a source of data. The names change in time and therefore their usage as identifiers as such is problematic. We present a solution for managing and using plant names as an ontology. The ontology is based on the TaxMeOn meta-ontology for biological names. In order to refer to organisms unambiguously and publish information as Linked Data on the web, the names are given URIs. The ontology is developed collaboratively and it supports the approval process and temporal tracking of the common names. We introduce an ontology service of plant names for end-users and provide user interfaces and APIs for integrating the ontology into applications.

Ontology repositories, such as NCBO Bioportal, ONKI and Cupboard, help finding and using ontologies on the Semantic Web. However, currently each ontology repository constitutes a separate island with its own user interface, APIs, users, ontology languages and set of ontologies. Because there is not a universal way to access all ontology repositories, doing global search, browsing, and inference over all available ontology repositories turns out to be technically difficult and is generally not done. Ontologies are not reused as much as they could and hence the full potential of ontologies is not achieved. To address the problem, we propose the Normalized Ontology Repository (NOR) approach to make the ontology repositories universally accessible while maintaining their unique functionalities and strengths. The SKOS language is used as the lowest common denominator for presenting the ontologies. In addition, a simple API for searching and accessing the ontologies is defined. As a proof-of-concept evaluation, we present three case implementations to demonstrate the NOR approach: 1) the distributed architecture of the ONKI repository, 2) the metasearch for ONKI and NCBO Bioportal, and 3) publishing informal ontological concept collections as NOR end-points, demonstrated with the semantic portal CultureSampo and the metadata editor SAHA.

Ontologiat ovat keskeinen osa semanttista webiä: ne toimivat yhteisinä jaettuina käsitteistöinä, joiden avulla tietokoneet voivat käsitellä tietoa älykkäämmin. Jotta eri toimijat voivat hyödyntää yhteisiä käsitteistöjä sovelluksissaan, ontologiat on julkaistava heidän käyttöönsä. Yksinkertaisimmillaan ontologiat voidaan julkaista tiedostomuodossa. Tällöin jokainen toimija joutuu toteuttamaan itse toiminnallisuuksia ontologioiden hyödyntämiseen. Koska osa toiminnallisuuksista on yleisiä, useissa järjestelmissä toistuvia, niiden toteuttaminen valmiina palveluina on mielekästä. Palveluita voidaan tarjota ihmiskäyttäjille käyttöliittymäkomponentteina sekä ohjelmalliseen käyttöön rajapintoina, joita käyttämällä toiminnallisuudet voidaan integroida asiakasjärjestelmiin. Tässä artikkelissa kuvataan ontologioiden käyttäjäryhmien tarpeita sekä ontologiapalveluiden toteutuksia. Yleisten ontologioiden käyttämiseen liittyvien toiminnallisuuksien tarjoamiseksi esitetään ontologiapalvelu ONKI, joka on osa Suomalaiset semanttisen webin ontologiat -hankesarjassa (FinnONTO, 2003–2012) kehitettyä ontologiainfrastruktuuria. Artikkeli perustuu Jouni Tuomisen pro gradu -työhön, jolle Tietojenkäsittelytieteen Seura ry myönsi lukuvuoden 2009–2010 pro gradu -palkinnon. Tutkimustyöhön ovat osallistuneet myös Kim Viljanen ja Eero Hyvönen.

We consider ontology evolution in a system of light-weight Linked Data ontologies, aligned with each other to form a larger ontology system. When one ontology changes, the human editor must keep track of the actual changes and of the modifications needed in the related ontologies in order to keep the system consistent. This paper presents an analysis tool MUTU, by which such changes and their potential effects on other ontologies can be found. Such an analysis is useful for the ontology editors for understanding the differences between ontology versions, and for updating linked ontologies when changes occurred in other components of an ontology system.

Biodiversity management requires the usage of heterogeneous biological information from multiple sources. Indexing, aggregating, and finding such information is based on names and taxonomic knowledge of organisms. However, taxonomies change in time due to new scientific findings, opinions of authorities, and changes in our conception about life forms. Furthermore, organism names and their meaning change in time, different authorities use different scientific names for the same taxon in different times, and various vernacular names are in use in different languages. This makes data integration and information retrieval difficult without detailed biological information. This paper introduces a meta-ontology for managing the names and taxonomies of organisms, and presents three applications for it: 1) publishing biological species lists as ontology services (ca. 20 taxonomies including more than 80,000 names), 2) collaborative management of the vernacular names of vascular plants (ca. 26,000 taxa), and 3) management of individual scientific name changes based on research results, covering a group of beetles. The applications are based on the databases of the Finnish Museum of Natural History and are used in a living lab environment on the web.

Ontologies and vocabularies are a key resource for creating interoperable metadata on the Semantic Web. To make finding and using ontologies easier, the idea of Ontology Repositories has been introduced with current implementations including e.g. the NCBO Bioportal, ONKI and Cupboard. There is a genuine need for different kinds of Ontology Repositories, each focusing on different kinds specific user-needs, different ontologies and different organizational requirements which cannot be addressed by a single general implementation. However, at the moment each Ontology Repository is a separate island with its own user interfaces and APIs. They also use varying ontology languages such as OWL, SKOS, and RDF Schema. Due to this, global search, browsing, and inference over the repositories is difficult and generally not done which means that, for example, finding and reusing existing ontologies becomes difficult. To address the problems, we have developed a loosely coupled Network of Ontology Repositories (NOR) architecture that makes the repositories globally interoperable while maintaining their unique functionalities and strengths. To participate in the network, each ontology repository is required to implement a shared API. As a proof-of-concept evaluation, we present three case implementations demonstrating different aspects of the NOR approach: 1) internal distributed architecture of ONKI, 2) global search of ONKI and NCBO Bioportal, 3) publishing non-ontological concept collections as NOR endpoints, demonstrated with the semantic portal CultureSampo and the metadata editor SAHA.

Ontologies and vocabularies are a key resource for creating interoperable metadata on the Semantic Web. To make the finding and using ontologies easier, the idea of Ontology Repositories have been introduced with current implementations including e.g. the NCBO Bioportal, ONKI and Cupboard. However, at the moment each ontology repository is a separate island with its own user interfaces and APIs. They also use varying ontology languages such as OWL, SKOS, RDF Schema and others. Due to this, global search, browsing, and inference over the repositories is difficult and generally not done. At the same time, there is a genuine need for different kinds of Ontology Repositories, each focusing on different kinds specific user-needs, different ontologies and different organizational requirements which can not be addressed by a single global implementation. Since there are benefits of having interoperability among the repositories, we have developed a loosely coupled Network of Ontology Repository (NOR) architecture that makes the repositories globally interoperable while maintaining their unique functionalities and strengths. To participate in the network, each ontology repository is required to implement a shared API. As a proof-of-concept, we present a global metasearch prototype for searching simultaneously hundreds of ontologies in the ONKI and NCBO Bioportal repositories.

Finding ontologies and concepts from a collection of ontologies is a recurring task in many use cases, such as content indexing, searching, and ontology developing. To facilitate this, efficient search and browsing methods are needed. This paper introduces ONKI2, an ontology browser providing a user interface for a repository of ontologies. The system provides a multi-facet search facility for finding an ontology. Finding concepts is supported by autocompletion-based text search that can be refined with additional restrictions. ONKI2 is in use in the Finnish Ontology Library Service ONKI for a collection of 79 ontologies and vocabularies.

Ontology repository systems are used for publishing and sharing ontologies. However, currently the repositories form separate islands of ontologies, which hinders the user from finding and utilizing the most suitable ontological concepts and ontologies on a global level. In contrast, this paper presents the idea of creating a network of Linked Open Ontology Services (LOOS) based on a set of ontology services that publish their content via a shared API. This facilitates global search and browsing over all ontologies in the network. LOOS has been implemented in the National Finnish Ontology Service ONKI serving currently 79 ontologies.

Ontology repository systems are used for publishing and sharing ontologies and vocabularies for content indexing, information retrieval, content integration, and other purposes. However, interlinking these distributed repositories to provide global search and browsing over the repositories has not been made. In the spirit of Linked Open Data, we propose creating a network of Linked Open Ontology Services (LOOS) consisting of ontology repositories that publish their content using a shared API. To test the approach, we have defined an HTTP API and present a proof-of-concept implementation consisting of three client applications that are used for accessing a LOOS network of over 50 ontology servers, part of the Ontology Library Service ONKI.

Ontologiat luovat semanttisen webin perustan: ne toimivat yhteisinä jaettuina käsitteistöinä, joiden avulla tietokoneet voivat käsitellä tietoa älykkäämmin. Jotta eri toimijat voivat hyödyntää yhteisiä käsitteistöjä sovelluksissaan, ontologiat on julkaistava heidän käyttöönsä. Yksinkertaisimmillaan ontologiat voidaan julkaista datana, tiedostomuodossa. Tällöin jokainen toimija joutuu toteuttamaan itse toiminnallisuuksia ontologioiden hyödyntämiseen. Osa toiminnallisuuksista on yleisiä, useissa järjestelmissä toistuvia, kuten ontologian visualisointi, selaaminen ja käsitehaku. On kuitenkin kustannustehokkaampaa toteuttaa yleisiä ontologiatoiminnallisuuksia valmiina palveluina. Palveluita voidaan tarjota ihmiskäyttäjille käyttöliittymäkomponentteina sekä ohjelmalliseen käyttöön rajapintoina, joita käyttämällä toiminnallisuudet voidaan integroida asiakasjärjestelmiin. Lisäksi käytettäessä ontologioita palveluina toimijoiden käytössä on aina ontologioiden ajantasaiset versiot. Tässä tutkielmassa kuvataan ontologioiden käyttäjäryhmien -- ontologioiden kehittäjien, tiedon annotoijien, tiedon hakijoiden ja semanttisen webin sovellusten kehittäjien -- tarpeita sekä esitellään ontologioiden hyödyntämiseen kehitettyjä sovelluksia. Yleisten ontologioiden käyttämiseen liittyvien toiminnallisuuksien tarjoamiseksi esitetään ontologiapalvelu ONKI, joka julkistettiin virallisesti käyttöön syyskuussa 2008.

CULTURESAMPO is an application demonstration of a national level publication system of cultural heritage contents on the Web, based on ideas and technologies of the Semantic (Web and) Web 2.0. On the semantic side, the system presents new solutions to interoperability problems of dealing with multiple ontologies of different domains, and to problems of integrating multiple metadata schemas and cross-domain content into a homogeneous semantic portal. A novelty of the system is to use semantic models based on events and narrative process descriptions for modeling and visualizing cultural phenomena, and for semantic recommendations. On the Web 2.0 side, CULTURESAMPO proposes and demonstrates a content creation process for collaborative, distributed ontology and content development including different memory organizations and citizens. The system provides the cultural heritage contents to end-users in a new way through multiple (nine) thematic perspectives, based on semantic visualizations. Furthermore, CULTURESAMPO services are available for external web-applications to use through semantic AJAX widgets.

Vocabularies are the building blocks of the Semantic Web providing shared terminological resources for content indexing, information retrieval, data exchange, and content integration. Most semantic web applications in practical use are based on lightweight ontologies and, more recently, on the Simple Knowledge Organization System (SKOS) data model being standardized by W3C. Easy and cost-efficient publication, integration, and utilization methods of vocabulary services are therefore highly important for the proliferation of the Semantic Web. This paper presents the ONKI SKOS Server for these tasks. Using ONKI SKOS, a SKOS vocabulary or a lightweight ontology can be published on the web as ready-to-use services in a matter of minutes. The services include not only a browser for human usage, but also Web Service and AJAX interfaces for concept finding, selecting and transporting resources from the ONKI SKOS Server to connected systems. Code generation services for AJAX and Web Service APIs are provided automatically, too. ONKI SKOS services are also used for semantic query expansion in information retrieval tasks. The idea of publishing ontologies as services is analogous to Google Maps. In our case, however, vocabulary services are provided and mashed-up in applications. ONKI SKOS was published in the beginning of 2008 and is to our knowledge the first generic SKOS server of its kind. The system has been used to publish and utilize some 60 vocabularies and ontologies in the National Finnish Ontology Service ONKI www.yso.fi.

This paper discusses problems of creating and using ontology library services in production use. One approach to a solution is presented with an online implementation--the Finnish Ontology Library Service ONKI--that is in pilot use on a national level in Finland. ONKI contributes to previous research on ontology libraries in many ways: First, mashup and web service support with various tools is provided for cost-efficient utilization of ontologies in indexing and search applications. Second, services covering the different phases of the ontology life cycle are provided. Third, the services are provided and used in real world applications on a national scale. Fourth, the ontology framework is being developed by a collaborative effort by organizations representing different application domains, such as health, culture, and business.

In this paper we present an ontology-based query expansion widget which utilizes the ontologies published in the ONKI Ontology Service. The widget can be integrated into a web page, e.g. a search system of a museum catalogue, enhancing the page by providing a query expansion functionality. We have tested the system with general, domain-specific and spatio-temporal ontologies.

We present an overview of CultureSampo, an ambitious system for creating a collective semantic memory of the cultural heritage of a nation on the Semantic Web 2.0, combining ideas underlying the Semantic Web and the Web 2.0. The system addresses the semantic web challenge of aggregating highly heterogeneous, cross-domain cultural heritage collections and other contents into a semantically rich intelligent system for human and machine users. At the same time, CultureSampo is an approach to solve the social and practical Web 2.0 challenge of organizing the underlying collaborative ontology development and content creation work of memory organizations and citizens. This paper focuses on CultureSampo’s search, recommendation, and visualization services for the end-users. The key idea here is to access cultural heritage on the Semantic Web through nine “thematic perspectives”, such as places on the maps, the social network of cultural persons, timelines, and narrative texts, e.g. biographies and literary works.

This paper presents an overview of the SemanticWeb 2.0 application CultureSampo, an ambitious system for creating a collective semantic memory of the cultural heritage of a nation on the Semantic Web 2.0, combining ideas underlying the Semantic Web and the Web 2.0. The system addresses the semantic web challenge of aggregating highly heterogeneous, cross-domain cultural heritage content into a semantically rich intelligent system for human and machine users. At the same time, CultureSampo is an approach to solve the social and practical Web 2.0 challenge of organizing the underlying collaborative ontology development and content creation work of memory organizations and citizens.

Ontologies aim to capture knowledge about things and their relationships. Publishing ontologies on the Semantic Web enables people and organizations to use shared ontologies in annotating e.g. photographs, videos, music, and other types of cultural objects. Search engines also use relationships provided by ontologies in semantic search, e.g. for query expansion or for view-based search. However, building ontologies is a time-consuming process, and it should be helped by automatic finding of interesting, possible relationships. Finding the correct concept for annotation purposes is helped by subsumption and partonomy hierarchies and associative relationships. In this paper we show how an analysis of co-occurrences of concepts in annotations can be used to provide interesting relationships for enriching ontological structures. We use association rule mining techniques and test the idea using a set of annotations of cultural objects in CULTURESAMPO portal and the Finnish General Upper Ontology YSO. The results are visualized in the ONKI SKOS browser to give an additional layer on top of the original relationships of the YSO ontology. An analysis shows that best ranked relationships should also be included in the ontology as subclassof or associative relationships.

This paper presents solutions and lessons learned in FinnONTO project carried out in Finland in 2003–2007. The paper focuses on three aspects of interoperability of digital collections. First, transforming thesauri to ontologies. Second, publishing ontologies for the use of indexers and content providers. Third, ontology based methods for improving end user access to digital collections.  The first aspect is analysed through case studies done with Finnish thesauri. The second is discussed by presenting the ONKI ontology server. The last aspect is demonstrated in the scope of the semantic portal CultureSampo for publishing cultural heritrage on the Semantic Web.

This paper presents the national level cross-domain ontology and ontology service infrastructure ONKI used in Finland. The novelty of ONKI is based on two ideas. First, the core ontologies are developed collaboratively by experts transforming thesauri into mutually aligned lightweight ontologies, based on a large top ontology that is extended by various domain specific ontologies. Second, the National Ontology Service ONKI has been implemented for publishing ontologies cost-efficiently as ready to use services. ONKI provides legacy and other applications with ready to use functionalities for using ontologies on the HTML level by Ajax and semantic widgets. ONKI has been used in various applications for creating mash-up applications in a way analogous to using Google Maps, but in our case external applications are mashed-up with ontology support for indexing and information retrieval.

This paper presents the Semantic Web 2.0 application CULTURESAMPO, an ambitious system of creating a collective semantic memory of the cultural heritage of a nation on the Semantic Web 2.0, combining ideas underlying the Semantic Web and the Web 2.0. The system addresses the semantic challenge of aggregating highly heterogeneous, cross-domain cultural heritage into a semantically rich intelligent system for human and machine users. At the same time, CULTURESAMPO is an approach to solve the social and practical Web 2.0 challenge of organizing the underlying collaborative ontology development and content creation work of memory organizations and citizens.

Thesauri and other controlled vocabularies act as building blocks of the Semantic Web by providing shared terminology for facilitating information retrieval, data exchange and integration. Representation and publishing methods are needed for utilizing thesauri efficiently, e.g., in content indexing and searching. W3C has provided the Simple Knowledge Organization System (SKOS) data model for expressing concept schemes, such as thesauri. A standard representation format for thesauri eliminates the need for implementing thesaurus specific rules or applications for processing them. However, there do not exist general tools which provide out of the box support for publishing and utilizing SKOS vocabularies in applications, without needing to implement application specific user interfaces for end users. For solving this problem the ONKI-SKOS server is presented.

The Semantic Web is based on using ontologies for enabling semantically disambiguated data exchange between distributed systems on the web. This requires efficient means for publishing ontologies on the web to ensure the availability, sharing and acceptance of the ontologies. Support services are needed for utilizing ontologies easily and cost-effectively in applications and legacy systems lacking ontology support. To address these vital needs, this paper presents the ONKI ontology service which provides ready-to-use mash-up functionalities, such as semantic disambiguation, concept finding and concept fetching as ready-to-use web widgets for adding ontology support to e.g. HTML forms using JavaScript. Two implementations of the ONKI Server are presented: ONKI-SKOS for ontologies presented in the Simple Knowledge Organization System (SKOS) language and ONKI-Geo for geographical ontologies with a map interface. The presented ONKI systems are operational on the web, used in the National Finnish Ontology Service. They have been successfully used in several pilot applications.

This article presents the vision and results of creating a national level cross-domain ontology service infrastructure in Finland in the FinnONTO project. The novelty of the infrastructure is based on two ideas. First, a system of open source core ontologies is being developed by transforming thesauri into mutually aligned lightweight ontologies, including a top ontology of 20,000 concepts that is extended by various domain specific ontologies. Second, the ONKI Ontology Server framework for publishing ontologies as ready to use services has been designed and implemented. ONKI provides legacy and other applications with ready to use functionalities for using ontologies on the user interface level as semantic widgets. The idea is to use ONKI for creating mash-up applications in a way analogous to using Google or Yahoo Maps, but in our case external applications are mashed-up with ontology support. The ontology framework presented is operational on the web and is being used in creating the application demonstrations.

Cultural heritage is by nature strongly interlinked, e.g. thematically and historically, but at the same time distributed in heterogeneous collections of different memory organizations at different locations. In order to provide the end-users with aggregated homogeneous views to distributed heterogeneous contents, semantic portals have been created successfully based on metadata and shared (or aligned) ontologies. This paper discusses two problems encountered in such a distributed semantic content creation environment. First, during the content creation work, how could a publisher start using shared ontologies in legacy cataloguing and annotation systems that do not support ontologies. Second, during content publication, how could a publisher re-use the aggregated content in its own legacy publication system, e.g., on the ordinary web pages of a museum or in a collection browser. As a solution, we present the ONKI Ontology Server for adding shared ontological annotation functionalities to legacy cataloguing systems in a practical, cost-efficient and lightweight way. For distributed publishing of the aggregated semantic portal services, we introduce the lightweight mash-up web widget components called floatlets . A major idea behind both the ONKI functionalities and floatlets is that they can be easily integrated with legacy systems on the user interface level, in the same spirit as e.g. Google Maps.

Producing semantic metadata requires efficient methods, e.g., concept finding, for accessing and using ontologies. To add such functionalities to metadata applications such as cataloging systems in museums, we propose a \emphmash-up approach where ready-to-use user interface components for using specific ontologies are made available to be integrated into applications. As a proof-of-concept, we present the \emphOntology Service ONKI wich implements semantic autocompletion concept search and concept browsing for ontologies as shared mash-up components.

A lot of functionality is needed when an application, such as a museum cataloguing system, is extended with semantic capabilities, for example ontological indexing functionality or multi-facet search. To avoid duplicate work and to enable easy and cost-efficient integration of information systems with the Semantic Web, we propose a web widget approach. Here, data sources are combined with functionality into readyto-use software components that allow adding semantic functionality to systems with just a few lines of code. As a proof of the concept, we present a collection of general semantic web widgets and case applications that use them, such as the ontology server ONKI, the annotation editor SAHA and the culture portal CultureSampo.

The Semantic Web is based on using shared ontologies for enabling semantically disambiguated data exchange between distributed systems on the web. This requires, from the ontology publisher s viewpoint, efficient means for publishing ontologies on the web to ensure the availability and acceptance of the ontologies. From the ontology user s viewpoint, support services are needed for utilizing ontologies easily and cost-effectively in the users own systems that are typically legacy systems without ontology support. This paper presents the ONKI ontology server for addressing these vital needs. For the publisher, ONKI provides a server and a Simple Knowledge Organization (SKOS) compatible light-weight ontology browser with ready-made web interfaces for making ontologies available both for human and machine users. For external legacy and other applications, ONKI provides centralized ontology services for semantic disambiguation, concept finding, and concept fetching. A major contribution of ONKI is to provide these services as ready-to-use functionalities for creating mash-up applications very cost-efficiently. Two prototypes of the system---ONKI-SKOS for all kinds of ontologies and ONKI-Geo for geographical ontologies with a map mash-up interface---are operational on the web and are currently being successfully used in several pilot applications.

This article presents the vision and results of creating the basis for a national semantic web content infrastructure in Finland in 2003-2007. The main elements of the infrastructure are shared and open metadata schemas, core ontologies, and public ontology services. Several practical applications testing and demonstrating the usefulness of the infrastructure are overviewed in the fields of eCulture, eHealth, eGovernment, eLearning, and eCommerce.

We present ONKI ontology server, a mash-up approach for integrating ontology library services with semantic web applications. The idea of ONKI is to provide applications with ready-to-use ontology service functionalities, such as semantic autocompletion, browsing, and annotation support, at the user interface level using AJAX mash-up technologies. The system is being integrated with various semantic web applications.